Manufacture of gold leaf



Oct. 28, 1924;

F. DEMEL MANUFACTURE OF GOLD LEA Filed ct. 2.9

. zzr` fwemw" Jamel Patented @et 2%, 1924.

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FRIEDRICH DEMEL, F TWICKENEAM, ENGLAND, ASSIGNOR 0F ONE-HALF TO'BICEARD1 TmDALL LEIGHTO-N, OF HOVE, SUSSEX, ENGLAND.

MANUFACTURE or connl LEAF.

Application inea october 29,1923. serial no. 671,550.

To all whom z't concem:

Be it known that I, FRIEDRICH Dimm., a

' subject of the King of Great Britain, residing at Twickenham,ltngland, have invented certain new and useful Improvements Relate ingto the Manufacture of Gold Leaf, of which the following is aspecification.

In United States Specification No. 198,209 dated 3rd October 1877 isdescribed a process for making gold leaf by electrolytic deposition ofgold. In principle the process consists in depositing the metal upon asuitable substance and subsequently removing Ysuch substance by heat orsolvent. Copper in thin sheets is stated to be a suitable substance; thegold is to be deposited on one side of the sheet which is then to beiioated copper side downwardsm on a bath of dilutenitric acid; the acidissolves the copper, leaving the gold oating in the form of leaf. 1

, The statement is not suflicient to enable the reader to make gold leafbecause it contains no direction as to how the copper sheet is to begilded.

It is essential that the gilding shall be strictly confined to one faceof the base metal, and since the other face has to be dissolvedprotective varnishes or the like are out of the question or greatlycomplicate the operation. By this invention a band or strip of basemetal unprotected by varnishes or the like is gilded on one face only bybringing the face ,which is to be gilded into contact with anelectrolytic bath under such conditions that the liquid cannot flow overthe edges of the band on to the face which isto remain without gilding.

ln the accompanying diagrammatic drawings, Fig.- 14 represents asectional elevation of one form of apparatus suitable for carryin'goutthe invention and Fig. 2 i'san end view and Fig. 3 a side view of amodlfied portion of the apparatus. v

ln Fig. 1, a silver band ai which conveniently is not less than 0.0005inch or more than 0.001 inch, is originally wound up on drum b and isunwound therefrom by-being wound up on drum c. As it leaves the drum bit is guided by rollers d on to the surface of ,a bath of gold solutioneY which may suitably contain 4 grams of the double cyanide of gold andpotassium per litre. The liquid is prevented by surface tension eectsfrom Howing onto the upper surface of the band.- TheI surface of theband which is in contact with the surface of the liquid is made acathode by connecting the metallic drum b with the negative terminal ofa source of electric current. The anode isa carbon plate fperforated asat f and immersed in the gold solu-y tion at a-short distance ifrom thesurface of the solution.; it is connected with the positive terminal ofthe source of electric current.l Suitable electrical conditions are anE. M. F. of 1.5 volts and a current density of 0.08 ampere per squaredecimetre of the silver` cathode. To ensure uniform maintenance of' bathas homogeneous as possible in respect of.

its composition an agitatorconsisting of a plate of about the samedimensions as the anode f may be raised and lowered continuously orintermittently by any suitable mechanism operating on its stem h but notindicated in the drawing; the perforations in the anode permit passageof the solution during the up and down movement of the agitator.

As the gilded silver band leaves the electrolytic bath it passes over aguide roller z into a bath of water lc and then round a roller 7csubmerged in this water. It now leaves the water and is guided by aroller Z on to a drying drum msuitably heated by steam, electric currentor otherwise, from which drum it is wound on the drum c. v

I Figs. 2 and 3 illustrate a modified method of carrying out theinvention, in which the face of the band which is to remain ungilded ispressed against a drum having an elastic surface, in which the edges ofthe band are more or less embedded thus reventing flow of liquid ontothe said ace.

rThe drum fn, consists of a spool-sha ed core 0 slipped into a rubbertube p WhitJ is tied l tightly on to the ends of the spool. There isthus formed a pneumatic cushion -which can be inflated through a valve gof well-known construction. The band a is caused by rollers fr to passaround the greater part of I nordsee the drum `which nevolvesinthe-loathe. The ofthe hand to press against the elastic rest of theapparatus resemlolesf` thatshown iii Fig, h v

'lt has heen assumed in this description.

thatpure old leaf is .to be made.. @emmer-- cial gold eat is strictly seakin ,an alloy and when this 'is' require the e ectrolytic fjloath'must he so modified in com osition that gold alloyed or mixed witht e requisite have nothin other-metal or metals, such as copper.. orf:silver or tooth is deposited. -'ll`h e necessary modifications are knownto electrogilders and need not he detailed here since they to do withthe invention.

Having t us fully described the nature offmy said invention and thehest'means l, hnovvforlcarrying the' same into practical electrolyte.,

, i apparatus .ai sisamiyaniy gating on one surface a loand of hasemetal, ofl which hand the other surface is unprotected hy an adhesivecoating, comprisingf an veleotrolytic-hath 'and means for causing thehand to travel through the hath with V'one only of its faces incontactWitliuthe' 2; Apparatus for electr'olyticallyv gilding on-one surface aloand of hase metal, 'of

" which hand the other lsurface is unprotected hy an adhesive coating,comprisingr an elecy trolytic hath and means includino an elasticsurface against which oneface or said hand. hears, said means and saidhand losing togather movable throu lisaid hathrl 3A Apparatus `for eectrolytically gilding on one surface a. hand of hase metal, of whichhand the other surface is unprotected loy an adhesive coating,comprising an electrol tic hath, va drum 'in said ath and-free torotate'ahout its axis,

said drum having an elastic surface on itsperiphery, means for "causinthe metal han to travel through said hat and means for causing one faceof the immersed portion 'from which the metal han source ot electricity;gui

partly immersed metal hand passes for causing the hand to i lie partlyin the electrolyte with one foes Iof the' portion which is immersedpresse against the elastic surface of said drum9 and means for iinnarting longitudinal movement to said han s.

5., tipparatus for electrolytically on one surface a hand of hasemetalgof which hand the other surface is unprotected hy an adhesivecoating, comprising1 a containing a solutiontor the electrodeposi-4 tionof gold, a horizontally disposed drum partly immersed in saidsolution mdto rotate about its airis, said drum having elastic surface on its-perihery? a roller roller upon which said hand is Wound9 one of the saidrollers being electrically conductc ing,'meansfo`r connecting theelectrically conducting Vroller to the negative pole of a which saidhand passes and causing hand' to lie partly in .thesolution with oneface of the immersed portion pressed the elastic surface of:` said anelectrode in the solution connected the positive pole of the source ofelectrioity9 and mevans for causing the metal hand to travel trom theunvnndingroller to the Winding roller.,

is unuound, of 1 e rollers overlln testimony. whereof ll have signedname to thisspeciiin'ation., Y

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